DISASSEMBLING YOUR ALTERNATOR

Undo pulley nut

To remove the pulley nut, wrap an old fan belt tightly round the pulley, then clamp the belt in a vice. Shock the pulley nut free using a socket, a T-bar and a soft-faced mallet. Unscrew and remove it.

Prise or pull off pulley

The pulley may be tight on the shaft. Pry it off with a pair of levers or stout screwdrivers – or deploy a puller. The beam-type in the photo is superior to a three-legged type. Don’t bend the fan pressings.

Remove brush unit

Unscrew and remove the brush unit, which may be combined with the regulator. Remove it smartly, angled to the front so the brushes can’t spring into any gap between the slip rings and casing.

Extract screws

Remove the screws that keep the casing halves together. Electrolytic corrosion may make them stubborn. Use a decent screwdriver. If you can support the casing, an impact driver is perfect.

Separate halves

Remove the brush holder and separate the casing halves. A rubber mallet may help, as may levering the halves with a pair of screwdrivers around the laminated iron stator band in the middle.

Watch the slip rings

The front half comes away with the rotor. The stator remains attached to the rear, along with the rectifier diodes. Be careful with the slip rings, especially if they’re made of soft graphite.